Giant
“dust devils” on Mars offer compelling clues as to the true cause of the
rille networks on Europa.

Perhaps
readers who have followed our discussion of “electric discharge
channels” on Jupiter’s moon Europa will recognize the bizarre
landscape in the pictures above. Can you identify which picture is
of the Europan surface?

The upper
picture is of particular interest because it shows how the force
that created the linear streaks was oblivious to other landscape
features. As observed by the electrical theorists, this is one of
the unsolved mysteries of rilles seen on many different bodies in
the solar system.

The lower
picture is also of special interest. For one thing, it is
reminiscent of the intimate connection between rille creation and
unusual cratering or etching patterns on planets, moons, and
asteroids. Note that many of the streaks appear to be little more
than chains of dark spots or dots, a pattern reminding us that many
rilles are little more than extended crater chains. Prior
theoretical assumptions have prevented planetary scientists from
either noticing the repeated pattern, or accounting for it.

So here is the
punchline. Neither picture above is of Europa, though the streaks
look almost exactly like the channel complexes on Europa. For
comparison with Europa, we’ve placed a good picture of Jupiter’s
moonhere.

Actually, both
pictures above depict regional landscapes on the planet Mars, where
towering “dust devils” have wandered across the surface, leaving
telltale tracks behind them. Investigators have been astonished at
the “electrical power” of these Everest-sized vortices eroding the
surface of Mars. Since the atmosphere of Mars is only one percent of
the Earth’s, it is certainly not wind alone that is producing
these effects on Mars! Indeed, the experts have struggled to find a
way for Martian “air” to move the surface soil at all. (See our next
Picture of the Day—“Electric Tornadoes on Mars”—for further
discussion of these mysteries).

The
similarities extend beyond the Europan rilles and surface
“scratches” on Mars to other common features and contexts. In
neither instance could the pits, dimples, or darkened
spots—often centered upon the linear impressions—be impact craters.
Most show a generally constant size. But electric arcing is known to
produce such crater patterns, including even the darkening of the
surface where it occurs. See Picture of the Day for November 30,
2004—Craters on Marsand for
July 2,2004—Craters
in the Lab

The
comparison of Europan channels and Martian “dust devil” tracks can
only underscore the new possibilities introduced by the electrical
hypothesis. And when it comes to the planet Mars, the applications
are virtually limitless.